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Diy Tuning


Ralph Wiggum

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  • Member For: 12y 1m 19d
  • Gender: Male

I've got to say I agree with Jet. The street might be fine for just getting the car running after some hardware changes, but I'd never be really doing any power stuff on the street. It's too inaccurate and just plain dangerous with any decent power. There's just too many factors at play and quite frankly I don't want to go directly past go, to jail in the big house The real work should always be done on a calibrated tool that's repeatable run after run which nobody should dispute.

One of my best mates just added a hub dyno to his arsenal and coming from a 4wd chassis dyno, the accuracy is mind blowing. We were really blown away with the repeatability of results and very finite changes you could actually see how the car was (or wasn't) responding. On a rolling road, they were often masked due to traction limitations, tire temperatures etc. I'm not surprised most shops now are going the hub route.

It's always good to check a car on the street afterwards as after all, they dont live on the dyno and driveability is key. Again, hard to give anything on the street a big hit, as your either torching tyres or rolling on speeds that Mr Plod wouldn't be happy about.

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  • Member For: 9y 9m 20d
  • Gender: Male
  • Location: Australia

That is the other thing, a roller dyno is so far from a proper load cell dyno. You really need a proper load cell to hit all possible cells and hold the car in a cell long enough to get steady state data. The repeatability of a roller dyno is trash as well, tyre temps, pressures and just plain position of the wheel on the roller all affect it too much. Obviously better than street tuning, but if you are going to find the time to hire a dyno, at least hire a modern load cell one.

 

The oem calibrators I've spoken to said it takes almost a second within each load point for the engine to reach true steady state, they said you can see it in the data that if it isn't held there long enough the data you get is wrong.

 

Where street tuning (or logging really) shines is creating a scatter plot of rpm vs load. You can then see if all you have properly scaled the breakpoints of the tables to match where you spend the majority of time. If the scatter plot is all bunched up in one corner you can quickly see where you should be rescaling and changing the break points. We added a "reinterpolate all referenced tables" function in the pcmtec editor exactly for this function, it auto re calculates all the cells to match the new axis, and when an axis is shared with multiple tables it does the whole lot for you.

Edited by rollex
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  • 3 weeks later...
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  • Member For: 11y 19d
  • Gender: Male
  • Location: Perth

Anyone know if a Barra ecu can be used on a completely different engine? As you can change the number of cylinders and firing order. It would need a different crank trigger and obviously a complete remap of the speed density tables but could it be possible?  

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  • Member For: 9y 9m 20d
  • Gender: Male
  • Location: Australia

Yes you can change the firing order and you can change the number of cylinders but you can't change how many outputs there are. Eg a V8 ECU could run an 8 or 6. But a 6 cyl ECU can only run a 6 cyl.

 

It would be fairly tricky to setup but it is possible.

 

There are people running the single cam motor from the AU off the barra PCM. There is a video on youtube showing how it worked. The engines are similar enough that it literally starts and runs without touching the speed density (surprised me). The VE must be withint 25% of the barra which means the O2 trims will get it close enough to idle and run, wouldn't want to give it a WOT run though.

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  • Member For: 11y 19d
  • Gender: Male
  • Location: Perth

I wanted to run it on a 4 cylinder, but I guess there is no way for the average person to go in there and define things like sensor types and crank trigger patterns. I know there are much better standalone ecu options out there but it was just an idea I was toying with 

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